PIE menu inside PIE menu
Call pie menu operator.
Example using the Text Editor &gt; Templates &gt; Python &gt; UI Menu Pie 
template.
Calls itself if clicked on and expands as another pie menu.
Note. Does not auto expand as a pie menu.
import bpy
from bpy.types import Menu

# spawn an edit mode selection pie (run while object is in edit mode to get a valid output)


class VIEW3D_MT_PIE_template(Menu):
    # label is displayed at the center of the pie menu.
    bl_label = &quot;Select Mode&quot;

    def draw(self, context):
        layout = self.layout

        pie = layout.menu_pie()
        # operator_enum will just spread all available options
        # for the type enum of the operator on the pie
        pie.operator_enum(&quot;mesh.select_mode&quot;, &quot;type&quot;)

        # this one expands as a regular menu
        pie.menu('VIEW3D_MT_PIE_template')
        
        # this one when pressed expands as a pie menu (of self)
        op = pie.operator(&quot;wm.call_menu_pie&quot;)
        op.name = 'VIEW3D_MT_PIE_template'

def register():
    bpy.utils.register_class(VIEW3D_MT_PIE_template)


def unregister():
    bpy.utils.unregister_class(VIEW3D_MT_PIE_template)


if __name__ == &quot;__main__&quot;:
    register()

    bpy.ops.wm.call_menu_pie(name=&quot;VIEW3D_MT_PIE_template&quot;)